The present disclosure relates generally to the field of vehicle powertrain systems. More particularly, the present disclosure relates to hybrid vehicle powertrain systems utilizing an engine and a motor.
Most vehicles currently on the road require a relatively large internal combustion engine to produce power needed for rapid acceleration. The engine on a standard vehicle is typically sized for the peak power requirement. However, most drivers use the peak power of their engines for only a small portion (e.g., one percent) of their driving time. Large engines may be heavy and inefficient and may result in higher emissions and/or lower fuel economy.
Vehicle efficiency may be improved through the use of a hybrid system that utilizes both an electric motor and an engine. In some hybrid systems, an electric motor may provide power to drive the vehicle over a certain range of operating conditions and an engine may provide power to drive the vehicle over a different range of operating conditions (i.e., such that only one of the motor and the engine provide power at any given time). In other hybrid systems, a motor may assist an engine in providing power to drive the vehicle. Hybrid systems may be capable of delivering required power with a smaller engine than non-hybrid systems. Small engines may be lighter, have fewer cylinders, and/or normally operate closer to their maximum load than large engines. The use of small engines may improve the efficiency (e.g., emissions, fuel economy) of a vehicle.
It would be advantageous to provide an improved hybrid system for a vehicle that provides improved fuel economy and reduced emissions as compared to current hybrid systems.